Magnetoresistive Element Manufacturing Flatness
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Solution Overview
Problem
The manufacturing of thin-film magnetic heads with TMR or CPP-GMR structures faces challenges in achieving flatness of the upper shield layer, leading to unstable operations and reduced recording density due to asperities, which require costly planarization processes and thick cap layers.
Innovation Solution
The method involves forming an MR multi-layered structure with side surfaces perpendicular to the layer lamination plane, using a thinner first insulation layer and a thicker second insulation layer with a magnetic domain control bias layer, allowing for minimal or no planarization process and enhanced magnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional planarization processes (CMP) are used to achieve flatness of the upper shield layer, then flatness is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by forming the MR multi-layered structure with vertically perpendicular side surfaces before depositing the upper shield layer. This preliminary structural preparation ensures that the upper shield layer naturally forms with sufficient flatness during the deposition process itself, eliminating the need for subsequent CMP planarization processes.
Solution Approach 2:
The patent extracts and removes the complex CMP planarization process from the manufacturing sequence. By designing the MR multi-layered structure with vertically perpendicular side surfaces, the patent eliminates the harmful asperities that would otherwise require CMP processing, thereby simplifying the overall manufacturing process.
2Manufacturing precision
If CMP planarization process is performed to achieve flatness, then upper shield layer flatness is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs a disposable sacrificial layer (organic resin layer) that is easily removed after serving its purpose of defining the vertical side surfaces. This approach replaces expensive and time-consuming CMP processes with a simpler, more cost-effective methodology using temporary sacrificial materials that can be easily deposited and removed.
3Manufacturing precision
If thick cap layer is formed to enable planarization, then planarization can be performed, but MR element structure becomes more complex
Solution Approach 1:
The patent extracts and eliminates the need for thick cap layers by directly forming the MR multi-layered structure with vertically perpendicular side surfaces through controlled deposition. This approach removes the unnecessary thick cap layer that would otherwise be required to provide sufficient material for CMP planarization, thereby simplifying the overall structure.
4Ease of manufacture
If asperities are present in upper shield layer, then manufacturing is simpler, but MR element stability and resolution deteriorate
Solution Approach 1:
The patent applies preliminary action by forming the MR multi-layered structure with vertically perpendicular side surfaces before depositing the upper shield layer. This preliminary structural preparation prevents the formation of asperities during shield layer deposition, ensuring stable MR element operation and high resolution without requiring complex post-processing.
Solution Approach 2:
The patent applies preliminary anti-action by designing the vertical side surfaces to counteract and prevent the formation of asperities in the upper shield layer. The perpendicular geometry of the MR multi-layered structure acts as a preventive measure that eliminates the harmful effect of surface irregularities before they can develop during subsequent deposition processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a flat magnetic domain control bias layer without the need for extensive planarization, ensuring sufficient magnetic domain control and increased recording density without the necessity for costly planarization processes.
Implementation Method 1
giant magnetoresistive effect (GMR) thin-film magnetic heads with GMR read head elements are being improved. On the other hand, tunnel magnetoresistive effect (TMR) thin-film magnetic heads with TMR read head elements
Implementation Method 2
a step of depositing an MR multi-layer, a step of patterning the deposited MR multi-layer by milling with a mask to form an MR multi-layered structure
Data Source
AI summary
A manufacturing method of an MR element in which current flows in a direction perpendicular to layer planes, includes a step of forming on a lower electrode layer an MR multi-layered structure with side surfaces substantially perpendicular to the layer lamination plane, a step of forming a first insulation layer on at least the side surfaces of the formed MR multi-layered structure, a step of forming a second insulation layer and a magnetic domain control bias layer on the lower electrode layer, and a step of forming an upper electrode layer on the MR multi-layered structure and the magnetic domain control bias layer.